mic841/842 comparator with 1.25% reference and adjustable hysteresis teeny ? is a trademark of micrel, inc. micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel +1 (408) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micrel.com general description the mic841 and mic842 are micropower, precision voltage comparators with an on-chip voltage reference. both devices are intended for voltage monitoring applications. external resistors are used to set the voltage monitor threshold. when the threshold is crossed, the outputs switch polarity. the mic842 incorporates a voltage reference and comparator with fixed internal hysteresis; two external resistors are used to set the switching threshold voltage. the mic841 provides a similar function with user adjustable hysteresis; this part requires three external resistors to set the upper and lower thresholds (the difference between the threshold voltages being the hysteresis voltage). both the mic841 and mic842 are available with push-pull or open-drain output stage. the push-pull output stage is configured either active high or active low; the open-drain output stage is only configured active low. supply current is extremely low (1.5 a, typical), making it ideal for portable applications. the mic841/2 is supplied in micrel?s teeny? 5-pin sc-70 package. data sheets and support documentation are found on the micrel web site: www.micrel.com . features ? 1.5v to 5.5v operating range ? 1.5 a typical supply current ? 1.25% voltage threshold accuracy ? 10na max input leakage current over temperature ? 10s propagation delay ? externally adjustable hysteresis (mic841) ? internal 20mv hysteresis (mic842) ? output options - push-pull, active high - push-pull, active low - open drain, active low ? open drain output can be pulled to 6v regardless of v dd ? immune to brief input transients ? teeny? 5-pin sc-70 package applications ? smart phones ? pdas ? precision battery monitoring ? battery chargers ______________________________________________________________________________________________________________________ typical application threshold detection with adjustable hysteresis threshold detector with internal fixed hysteresis april 2011 m9999-042711-c
micrel, inc. mic841/2 april 2011 2 m9999-042711-c ordering information part number marking hysteresis adjustment output stage output function temperature range pb-free package mic841hbc5 b13 external push pull active high ?40 to +85c sc-70-5 mic841lbc5 b14 external push pull active low ?40 to +85c sc-70-5 mic841nbc5 b15 external open drain active high ?40 to +85c sc-70-5 mic842hbc5 b16 internal push pull active high ?40 to +85c sc-70-5 mic842lbc5 b17 internal push pull active low ?40 to +85c sc-70-5 mic842nbc5 b18 internal open drain active high ?40 to +85c sc-70-5 mic841hyc5 b 13 external push pull active high ?40 to +85c 9 sc-70-5 mic841lyc5 b 14 external push pull active low ?40 to +85c 9 sc-70-5 MIC841NYC5 b 15 external open drain active high ?40 to +85c 9 sc-70-5 mic842hyc5 b 16 internal push pull active high ?40 to +85c 9 sc-70-5 mic842lyc5 b 17 internal push pull active low ?40 to +85c 9 sc-70-5 mic842nyc5 b 18 internal open drain active high ?40 to +85c 9 sc-70-5
micrel, inc. mic841/2 april 2011 3 m9999-042711-c pin configuration mic841 mic842 sc-70-5 (c5) sc-70-5 (c5) pin description mic841 pin number pin name pin function 1 hth high threshold input. hth and lth monitor external voltages. 2 gnd ground. 3 lth low threshold input. lth and hth monitor external voltages. out (?h? version) active-low push-pu ll output. out asserts low when v lth < v ref . out remains low until v hth > v ref . out (?l? version) active-high push-pull output. out asserts high when v ltl < v ref . out remains high until v hth > v ref . 4 out (?n? version) active-low , open-drain output. out asserts low when v lth < v ref . out remains low until v hth > v ref . 5 v dd power supply input pin description mic842 pin number pin name pin function 1 inp threshold input. inp monitors an external voltage. 2 gnd ground 3 nc no connect. not internally connected. out (?h? version) active-low, push-pu ll output. out asserts low when v inp < v ref . out remains low until v inp > (v ref + v hyst ). out (?l? version) active-high, push-p ull output. out asserts high when v inp < v ref . out remains high until v inp > (v ref + v hyst ). 4 out (?n? version) active-low , open-drain output. out asserts low when v inp < v ref . out remains low until v inp > (v ref + v hyst ). 5 v dd power supply input
micrel, inc. mic841/2 april 2011 4 m9999-042711-c absolute maximum ratings (1) supply voltage (v dd )....................................... ?0.3v to +7v input voltage (v inp, v lth, v ltl ) .......................................+7v output current (i out ) .................................................20ma storage temperature (t s )........................ ?65c to +150c junction temperature (t j ) ........................................ 150c esd rating, note 3 ....................................................... 1kv operating ratings (2) supply voltage (v dd )................................... +1.5v to +5.5v input voltage (v inp v lth, v ltl )........................... ?0.3v to 6v v out (?h? and ?l? ve rsions)............................................... v dd v out (?n? version) ............................................................. 6v ambient temperature range (t a ) ............. ?40c to +85c package thermal resistance ( ja ) .................... 256.5c/w electrical characteristics (4) 1.5v v dd 5.5v; t a = +25c, bold values indicate ?40c t a +85c, unless noted. symbol parameter condition min typ max units i dd supply current out put not asserted 1.5 3 a i inp input leakage current 0.005 10 na 0 c to 85 c 1.225 1.240 1.256 v v ref reference voltage ?40 c to 85 c 1.219 1.240 1.261 v v hyst hysteresis voltage, (note 5) mic842 only 8 20 35 mv v inp = 1.352v to 1.128v 12 s t d propagation delay v inp = 1.143v to 1.367v 8 s i sink = 1.6ma, v dd 1.6v 0.05 0.3 v output voltage-low i sink = 100 a, v dd 1.2v 0.005 0.4 v i source = 500 a, v dd 1.6v 0.99v dd v v out (note 6) output voltage-high i source = 50 a, v dd 1.2v 0.99v dd v notes: 1. exceeding the absolute maximum rating may damage the device. 2. the device is not guaranteed to function outside its operating rating. 3. devices are esd sensitive. handli ng precautions recommended. human body mo del, 1.5k in series with 100pf. 4. specification for packaged product only. 5. v hth = v ref + v hyst . 6. v dd operating range is 1.5v to 5.5v. output is guaranteed to be de-asserted down to v dd = 1.2v.
micrel, inc. mic841/2 april 2011 5 m9999-042711-c block diagrams
micrel, inc. mic841/2 april 2011 6 m9999-042711-c application information output the mic841n and mic842n outputs are an open-drain mosfet, so most applications will require a pull-up resistor. the value of the re sistor should not be too large or leakage effects may dominate. 470k ? is the maximum recommended value. note that the output of ?n? version may be pulled up as high as 6v regardless of the ics supply voltage. the ?h? and ?l? versions of the mic841 and mic842 have a push-pull output stage, with a diode clamped to v dd . thus, the maximum output voltage of the ?h? and ?l? versions is v dd . see ?electrical characteristics.? when working with large resistors on the input to the devices, a small amount of leakage current can cause voltage offsets that degrad e system accuracy. the maximum recommended tota l resistance from v in to ground is 3m ? . the accuracy of the resistors can be chosen based upon the accuracy required by the system. the inputs may be subjected to voltages as high as 6v steady-state without adverse effects of any kind regardless of the ics supply voltage. this applies even if the supply voltage is zero. this permits the situation in which the ic?s supply is turned off, but voltage is still present on the inputs. see ?e lectrical characteristics.? programming the mic841 thresholds the low-voltage threshold is calculated using: ? ? ? ? ? ? + ++ ? 3r2r 3r2r1r vv ref)lo(in the high-voltage threshold is calculated using: ? ? ? ? ? ? ++ ? 3r 3r2r1r vv ref)hi(in where, for both equations: in order to provide the additional criteria needed to solve for the resistor values, t he resistors can be selected such that they have a given total value, that is, r1 + r2 + r3 = r total . a value such as 1m for r total is a reasonable value because it draws minimum current but has no significant effect on accuracy. figure 1. mic841 example circuit once the desired trip points are determined, set the v in(hi) threshold first. for example, use a total of 1m = r1 + r2 + r3. for a typical single-cell lithium ion battery, 3.6v is a good ?high threshold? because at 3.6v the battery is moderately charged. solving for r3: ? ? ? ? ? ? ?? 3r m1 24.1v6.3v )hi(in r3 = 344k once r3 is determined, the equation for v in(lo) can be used to determine r2. a single lithium-ion cell, for example, should not be discharged below 2.5v. many applications limit the drain to 3.1v. using 3.1v for the v in(lo) threshold allows calculation of the two remaining resistor values. ? ? ? ? ? ? + ?? k3442r m1 24.1v1.3v )lo(in r2 = 56k 1m - (r2 - r3) = r1 r1 = 600k the accuracy of the resistors can be chosen based upon the accuracy required by the system.
micrel, inc. mic841/2 april 2011 7 m9999-042711-c v in out v in (lo) 0v 0v v in (hi) out 0v h and n versions l version v hysterisis figure 2. output response and hysteresis programming the mic842 thresholds the voltage threshold is calculated using: ? ? ? ? ? ? + ? 2r 2r1r vv ref)lo(in where: v ref = 1.240v figure 3. mic842 example circuit in order to provide the additional criteria needed to solve for the resistor values, the resistors can be selected such that they have a given total value, that is, r1 + r2 = r total . a value such as 1m ? for r total is a reasonable value because it draws minimum current but has no significant effect on accuracy. input transients the mic841/2 is inherently immune to very short negative-going ?glitches.? very brief transients may exceed the v in(lo) threshold without tripping the output. as shown in figure 4, the narrower the transient, the deeper the threshold overdrive that will be ignored by the mic841/2. the graph represents the typical allowable transient duration for a gi ven amount of threshold overdrive that will not generate an output. figure 4. input transient response
micrel, inc. mic841/2 april 2011 8 m9999-042711-c package information micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel +1 (408) 944-0800 fax +1 (408) 474-1000 web http://www.micrel.com micrel makes no representations or warranties with respect to t he accuracy or completeness of the information furnished in this data sheet. this information is not intended as a warr anty and micrel does not assume responsibility for its use. micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. no license, whether expre ss, implied, arising by estoppel or other wise, to any intellectual property rights is granted by this document. except as provided in micrel?s terms and conditions of sale for such products, mi crel assumes no liability whatsoever, and micrel disclaims any express or implied warranty relating to the sale and/or use of micrel products including l iability or warranties relating to fitness for a particular purpose, merchantability, or infringement of an y patent, copyright or other intellectual p roperty right. micrel products are not designed or authori zed for use as components in life support app liances, devices or systems where malfu nction of a product reasonably be expected to result in pers onal injury. life support devices or system s are devices or systems that (a) are in tended for surgical impla into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significan t injury to the user. a purchaser?s use or sale of micrel produc ts for use in life support app liances, devices or systems is a purchaser?s own risk a nd purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. can nt ? 2005 micrel, incorporated.
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